After months of French-American wrangling, NATO has finally agreed on the forum it wants to see for conventional arms reduction talks in Europe. On the first day of their biannual meeting, NATO foreign ministers proposed that the 23 NATO-Warsaw Pact nations negotiate arms cuts for the area from the Atlantic to the Urals, then report back to the 35-nation Conference on Security and Cooperation in Europe (CSCE) on the group's progress. This meets the US demand for alliance discipline in the arms cuts talks themselves. But it also assuages the sensitivities of the French - who belong to NATO's political alliance, but not, since 1966, to its military command - by placing these talks within a pan-European framework.

The 35 nation group, which includes neutral and nonaligned nations, will continue to deal with confidence-building measures as it did in the Stockholm conference that agreed on notification and inspection measures this fall. The smaller group will deal with the difficult questions of personnel and hardware cuts.

Not yet resolved, apparently, are the substantive aims NATO will be seeking in the conventional arms reduction negotiations. The communiqu'e issued yesterday sets forth only the most general objectives: ``elimination of disparities;'' a ``step-by-step'' process; ``focus on the elimination of the capability for surprise attack;'' taking into account and redressing ``regional imbalances;'' and ``effective verification.'' It does not address at all the hard questions of whether to reduce manpower, units, arms, or mobilization capability.

After a few weeks of reflection, European officials do not think that the Reykjavik summit's 10-year goal of a world without nuclear weapons (the Soviet version), or even just without ballistic missiles (the American version), is in danger of being realized. But the fact that the US was willing to discuss this with the Soviets over the heads of its European allies has convinced Europeans that the days of the American nuclear umbrella are numbered. And this, in turn, gives much more weight to Soviet conventional superiority in Europe - and makes it much more alarming to the Europeans.

The reason for this is that in Europe, the West's nuclear weapons have always been used to offset the Soviet conventional superiority. In the strategic balance, the purpose of the West's nuclear weapons is basically only to deter the Soviets from using their nuclear weapons out of fear of US nuclear retaliation. In the European balance, by contrast, the purpose of the West's nuclear weapons is also to deter any Soviet conventional attack.

NATO faces uncomfortable choices in the conventional balance. Politically, its populations will not accept the kind of increased military expenditures that would be needed to build up to Soviet-bloc levels of armaments. NATO therefore pins its hopes on arms control to build down Soviet superiority. Yet the West's inferiority provides little leverage to induce such action.

No timetable has been set for the new arms reduction negotiations. But the Soviet bloc will be eager to set them in motion - first, because the new forum gets the negotiations out of the 13-year-old Mutual and Balanced Force Reduction (MBFR) context in Vienna, and second, because such talks themselves help create pressures for military build-downs among democratic Western European populations.

The sluggish MBFR talks dealt only with the central front of the two Germanys, Czechoslovakia, Poland, and the Low Countries. The West likes this focus because Soviet conventional superiority is most threatening there. Moscow, by contrast, likes to deal with a broader geographical area in which the manpower is more equal and the Soviet concentration of 20 divisions in East Germany is less of an issue.